How much are you actually aware of the differences between the 6s and 7? You were on your third iPhone 7 and you believe that potentially they're all faulty? Have you considered that the iPhone 7 just has a different display over the other iPhones you've used in the past? The 7 naturally has a warmer tone to it if you research this thread and other threads.
I have used multiple iPhone 7's/7 Plus's and they are all somewhat yellowish in display.
I think you're going to find out not every iPhone is going to have the same with display, even if you are provided a fourth replacement iPhone. It doesn't necessarily mean there is an issue. Part of the reason may be the adhesive getting warmer when iPhone display is being used. As the other formum member above you stated, you may either adjust to it or it may dissipate over time.
Thanks for your response.
It's certainly noticeable between an iPhone 6 and my phone. The pictures I posted were two iPhone 7s beside each other, to illustrate that my screen in yellower than another iPhone 7. I'm aware that the 7 has a warmer white point than other earlier models, however, my concern was that my particular ones were warmer than other 7s (as the picture shows). I just thought I'd see if other people were still experiencing issues with new iPhone 7s. I'm completely open to the fact that the yellow may wear off(?) over time, as the 7s I have compared mine with have been in operation for a lot longer.
Is it common for the yellow to dissipate over time?